# HG changeset patch
# User Jun Wu <quark@fb.com>
# Date 2018-03-19 11:28:29
# Node ID 8d730f96e792f52f8dee5f02d80ff6b2e590371b
# Parent  6e137da59ad9a4f9a24ac73053a9add2d15cef5e

patch: move yielding "\n" to the end of loop

The original logic makes it harder to reason about - it yields the "\n"
character belonging to the last line in the next loop iteration.

The new code is in theory a little bit slower. But is more readable. It
makes the following changes easier to read.

Differential Revision: https://phab.mercurial-scm.org/D3210

diff --git a/mercurial/patch.py b/mercurial/patch.py
--- a/mercurial/patch.py
+++ b/mercurial/patch.py
@@ -2505,9 +2505,8 @@ def difflabel(func, *args, **kw):
         matches = {}
         if inlinecolor:
             matches = _findmatches(lines)
+        linecount = len(lines)
         for i, line in enumerate(lines):
-            if i != 0:
-                yield ('\n', '')
             if head:
                 if line.startswith('@'):
                     head = False
@@ -2546,6 +2545,8 @@ def difflabel(func, *args, **kw):
                 yield (line, '')
             if line != stripline:
                 yield (line[len(stripline):], 'diff.trailingwhitespace')
+            if i + 1 < linecount:
+                yield ('\n', '')
 
 def _findmatches(slist):
     '''Look for insertion matches to deletion and returns a dict of